Maint: port forwarding refactoring (#543)

- portforward package
- portforward run loop
- Less functional arguments and cycles

internal/portforward/state/state.go

@@ -0,0 +1,37 @@
+package state
+
+import (
+	"sync"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/loopstate"
+)
+
+var _ Manager = (*State)(nil)
+
+type Manager interface {
+	SettingsGetSetter
+	PortForwardedGetterSetter
+	StartDataGetterSetter
+}
+
+func New(statusApplier loopstate.Applier,
+	settings configuration.PortForwarding) *State {
+	return &State{
+		statusApplier: statusApplier,
+		settings:      settings,
+	}
+}
+
+type State struct {
+	statusApplier loopstate.Applier
+
+	settings   configuration.PortForwarding
+	settingsMu sync.RWMutex
+
+	portForwarded   uint16
+	portForwardedMu sync.RWMutex
+
+	startData   StartData
+	startDataMu sync.RWMutex
+}